No link between MMR vaccines and autism

Review rejects MMR autism link
Latest study finds no relationship between MMR vaccine and autism.
12 June 2002
JOHN WHITFIELD
Fear has caused UK vaccination rates to fall.
There is no link between the combined measles, mumps and rubella (MMR)
vaccine and autism or bowel disease, says the latest review of published
evidence.
In the UK, fears that the combined vaccine could trigger autism by causing
intestinal disease has caused infant vaccination rates to drop below 85%. To
prevent outbreaks of measles, mumps and rubella, which at worst can result
in brain damage, infertility and death, 95% vaccination is needed.
To address these concerns, the British Medical Journal Publishing Group
commissioned an analysis of the latest research from UK healthcare research
company Bazian1.
"We've found no evidence of a link," says epidemiologist Vivek Muthu of
Bazian. Muthu admits he thought there might be a case against the vaccine
before he began the study but says that for him, the scientific issue is now
settled.
The new analysis is "transparent and fair", says paediatric epidemiologist
Stuart Logan of University College London. "It gives clinicians and parents
a very good summary of what we know."
"We hope that parents are encouraged by these latest conclusions on the
safety of this vaccine," said a spokesman for the UK Department of Health.
Bazian researchers searched electronically and by hand for peer-reviewed
journal articles, government reports and other datasets on measles
vaccination - in total about 2,000 studies. They filtered the studies
according to a range of quality-control criteria, such as sample size,
whether a control group was used and how measurements were made.
Six studies on the link between MMR and autism or bowel problems made it
over this threshold. None showed any link between vaccination and disease.
Many showed the health benefits of vaccination.
We hope parents are encouraged by these latest conclusions on the safety of
this vaccine
UK Department of Health spokesman
The furore over the MMR vaccine and autism began in 1998, when a study of 12
autistic children noted that the onset of the condition in eight of them
followed the vaccination2. This study did not make the final cut in Bazian's
analysis, as it had no control group, the sample size was small, and the
conclusions were based on surveying parents up to eight years after
vaccination.
Weight of opinion
The finding is in line with the vast weight of scientific opinion. But, as
Logan remarks "people are still worried out of their wits" that the vaccine
may be dangerous.
This makes it worth carrying on investigating the topic, he says. A
multinational epidemiological study is underway at the moment. Ironically,
Logan adds, the decline in vaccination will aid research: it creates a
larger group of unvaccinated children to study.
The possibility that the MMR vaccine might cause disease in a small fraction
of the population is not yet ruled out. But in the absence of any idea of
what the risk factors might be, there's "no rational basis" on which to
build a search for them, says Alan Morris, who studies the molecular causes
of diseases at the University of Warwick, UK.
References
1. Donald, A. & Muthu, V. Clinical Evidence, 7, 331 - 340, (2002).
2. Wakefield, A. J. et al. Ileal-lymphoid-nodular hyperplasia,
non-specific colitis, and pervasive developmental disorder in children.
Lancet, 351, 637 - 641, (1998).
Nature News Service / Macmillan Magazines Ltd 2002
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